ubiquity crashed with DBusException in call_blocking(): org.freedesktop.DBus.Error.ServiceUnknown: The name :1.90 was not provided by any .service files

This bug occurs every time I click on "continue" on the screen "preparing to install", where I selected "install these drivers" and" download updates while installing. I have waited for about 10 minutes and Ubiquity apparently never continues to the next step.
Consequently, it is impossible for me to install Oneiric on my HP Elitebook 8560w at this point.

It might be worth noting that along side this bug, two other bugs occur:
1. #831754, occurs when opening Ubiquity.
2. #833295, occurs when opening Ubiquity.
3. This bug, in this order. Occurs when ticking both boxes on "Preparing to install" screen and clicking continue.

UPDATE: I figured out that the ticking the box "Install 3rd party software" causes this problem. Unticking it, I can continue with the installation process.

ProblemType: Crash
DistroRelease: Ubuntu 11.10
Package: ubiquity 2.7.15
ProcVersionSignature: Ubuntu 3.0.0-9.14-generic 3.0.3
Uname: Linux 3.0.0-9-generic x86_64
Architecture: amd64
CasperVersion: 1.279
Date: Wed Aug 24 19:24:05 2011
ExecutablePath: /usr/lib/ubiquity/bin/ubiquity
InterpreterPath: /usr/bin/python2.7
LiveMediaBuild: Ubuntu 11.10 "Oneiric Ocelot" - Alpha amd64 (20110824)
ProcCmdline: /usr/bin/python /usr/lib/ubiquity/bin/ubiquity gtk_ui
ProcEnviron: Error: [Errno 13] Permission denied: '/proc/13669/environ'
PythonArgs: ['/usr/lib/ubiquity/bin/ubiquity', 'gtk_ui']
SourcePackage: ubiquity
Title: ubiquity crashed with DBusException in call_blocking(): org.freedesktop.DBus.Error.ServiceUnknown: The name :1.90 was not provided by any .service files
UpgradeStatus: No upgrade log present (probably fresh install)
UserGroups: